METHODOLOGICAL AND OPERATIONAL ASPECTS OF PERMEATION MEASUREMENTS ON SILICALITE-1 MEMBRANES

Permeation measurements with zeolite membranes are evaluated by compar ing data obtained from different experimental methods: a batch method and the Wicke-Kallenbach method. The permeation of methane, ethane, pr opane and n-butane was studied between 270 and 625 K at pressures betw een 10 and 425 kPa. The experiments were performed in a continuous and discontinuous way, with and without the use of a sweep gas. From the comparison of the different techniques it was found that the sweep gas significantly influences the permeation of the feed component. This e ffect was found to be dependent on the nature of the sweep gas and on the magnitude of the counter permeation. The experimental configuratio n, such as the orientation of the composite membrane with respect to t he feed side, affects the local conditions at both sides of the zeolit e layer, resulting in quite different permeances. Only if these effect s are taken into account properly, intrinsic data on permeation throug h the zeolite layer can be obtained. (C) 1998 Elsevier Science B.V.